Systems for fuel injectors with fuel air heat exchangers

ABSTRACT

A system includes an air manifold, a fuel manifold, and a plurality of fuel injectors. At least one of the fuel injectors includes a heat exchanger portion for supplying compressed, cooled air form the heat exchanger portion to the air manifold. An air valve is operatively connected to an outlet of the air manifold for controlling release of air from the air manifold. A controller is operatively connected to the air valve, wherein the controller includes machine readable instructions configured to control the air valve to regulate flow of air through the air valve based on fuel temperatures in the fuel channel. The machine readable instructions can be configured to cause the controller to flow air through the air valve in a heat exchange mode if a fuel temperature in the fuel injectors is below a predetermined fuel temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 17/406,767filed Aug. 19, 2021 the content of which is incorporated by referenceherein in its entirety.

BACKGROUND 1. Field

The present disclosure relates generally to fuel and air systems for gasturbine engines, and more particularly to fuel injectors and fuel airheat exchanger systems for gas turbine engines.

2. Description of Related Art

A portion of the compressor discharge air in a gas turbine engine can bediverted from the main gas flow though the engine for various uses inthe engine and onboard an aircraft. However, this air is typically toohot to be of use in general applications. Fuel air heat exchangers canbe used to cool the diverted portion of compressed air. However, fuelair heat exchangers are not typically easy to retrofit on existingengine designs and this among other things leaves a need in the art forimproved systems and methods for fuel air heat exchange. This disclosureprovides a solution for this need.

SUMMARY

A system includes an air manifold, a fuel manifold, and a plurality offuel injectors. Each fuel injector is connected in fluid communicationto receive fuel from the fuel manifold. At least one fuel injector inthe plurality of fuel injectors includes a heat exchanger portionwherein an air channel and a fuel channel are in thermal communicationwith one another for heat exchange between fuel and air passing throughthe heat exchanger portion. The fuel channel passes from a fuel channelinlet, through the heat exchanger portion to a nozzle outlet. The airchannel passes from the heat exchanger portion, to an air channeloutlet. The respective inlet of the fuel channel is connected to thefuel manifold for fluid communication of fuel from the fuel manifold tothe nozzle outlet for combustion. The respective outlet of the airchannel is connected to the air manifold for fluid communication of airfrom the heat exchanger portion into the air manifold.

An air valve is operatively connected to an outlet of the air manifoldfor controlling release of air from the air manifold. A controller isoperatively connected to the air valve, wherein the controller includesmachine readable instructions configured to control the air valve toregulate flow of air through the air valve based on fuel temperatures inthe fuel channel. The machine readable instructions can be configured tocause the controller to flow air through the air valve in a heatexchange mode if a fuel temperature in the fuel injectors is below apredetermined fuel temperature.

The machine readable instructions can be configured to cause thecontroller to vary air flow rate through the air valve in the heatexchange mode to increase air flow through the air valve whilemaintaining fuel temperature below the predetermined limit. Atemperature sensor can be mounted in at least one of the fuel injectorsoperative to produce a signal indicative of fuel temperature in the fuelchannels of the fuel injectors. The controller can be operativelyconnected to receive the signal, wherein the machine readableinstructions are configured to control the air flow rate based on thesignal. The machine readable instructions can be configured to cause thecontroller to prevent air flow through the air valve in a neutral mode.

An auxiliary source of conditioned, compressed air can be included,selectively in fluid communication with the air manifold. The machinereadable instructions can be configured to prevent air flow out of theair manifold and instead flow air from the auxiliary source into the airmanifold in a fuel cooling mode. The auxiliary source of air can includean air cooling heat exchanger separate from the fuel injectors andoperative to cool compressor discharge air. A boost compressor can beconnected in fluid communication with the air cooling heat exchanger andoperative to raise pressure in a flow of air from the air cooling heatexchanger above compressor discharge air pressure. The boost compressorcan be in fluid communication with the air valve. The air valve can beconfigured to block flow out of the air manifold and admit air into theair manifold from the boost compressor for active cooling of fuel in theat least one fuel injector in the plurality of fuel injectors in thefuel cooling mode. The controller can be configured to initiate the fuelcooling mode based on a signal received from at least one temperaturesensor in the plurality of fuel injectors.

The system can include an engine case. The heat exchanger portion of theat least one fuel injector in the plurality of fuel injectors can beinside the engine case. The air manifold and fuel manifold can beoutside the engine case. The air manifold and the fuel manifold can bespaced apart from one another, with a gap between the air manifold andthe fuel manifold. A combustor dome wall can be included inside theengine case. A combustion space of a combustor can be defined on adownstream side of the combustor dome wall. Each fuel injector in theplurality of fuel injectors can include a nozzle outlet mountedproximate to and in fluid communication through the combustor dome walloperative to issue fuel into the combustion space. An inlet to the airchannel of the at least one fuel injector in the plurality of fuelinjectors can be located on an upstream side of the combustor dome wallopposite the combustion space.

A method of heat exchange for a gas turbine engine includes collectingair from a respective fuel air heat exchanger portion of at least onefuel injector in a plurality of fuel injectors into an air manifold. Themethod includes supplying air from the air manifold to one or moreexternal compressed air systems in a heat exchange mode.

The method can include varying flow of air through the air manifoldbased on fuel temperature in the plurality of fuel injectors. Modulatingflow of air can include increasing flow of air through the manifold iffuel temperature in the plurality of fuel injectors permits withoutexceeding a predetermined limit on fuel temperature.

The method can include preventing air flow through the air manifold in aneutral mode. In a fuel cooling mode, the method can include preventingair flow out of the air manifold and instead flowing air into the airmanifold. In the fuel cooling mode, cooling air from the air manifoldcan be flowed into the plurality of fuel injectors. The method caninclude supplying cooling air to the air manifold from compressordischarge air that is pressure boosted to above compressor discharge airpressure. The method can include cooling pressure boosted, compressordischarge air upstream of the air manifold in the fuel cooling mode.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,preferred embodiments thereof will be described in detail herein belowwith reference to certain figures, wherein:

FIGS. 1-3 are schematic cross-sectional views of an embodiment of asystem constructed in accordance with the present disclosure, showingfuel and air manifolds for a set of fuel injectors with an integratedfuel air heat exchangers extending into the engine case, showing thesystem in an air cooling mode, a neutral mode, and a fuel cooling mode,respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a partial view of an embodiment of a fuel injector inaccordance with the disclosure is shown in FIG. 1 and is designatedgenerally by reference character 100. Other embodiments of systems inaccordance with the disclosure, or aspects thereof, are provided inFIGS. 2-3 , as will be described. The systems and methods describedherein can be used to provide a supply of cool, compressed air fromcompressor discharge air for use on an engine and/or aircraft, usingheat exchangers in the fuel injectors, as well as techniques for coolingfuel in the fuel injectors.

The system 100 includes an air manifold 102, a fuel manifold 104, and aplurality of fuel injectors 106. Only two fuel injectors 106 are shownin the upper, annular cross-section of FIGS. 1-3 , however those skilledin the art will readily appreciate that any suitable number of fuelinjectors can be arranged around the annular engine axis. Each fuelinjector 106 is connected in fluid communication to receive fuel fromthe fuel manifold 104. At least one of the fuel injectors 106 includes aheat exchanger portion 108 wherein an air channel 110 and a fuel channel112 are in thermal communication with one another for heat exchangebetween fuel and air passing through the heat exchanger portion 108.While only one injector 106 needs to include a heat exchanger portion108, any number of the fuel injectors 106, including all of them, caninclude a respective heat exchanger portion 108. The fuel channel 112passes from a fuel channel inlet 114, through a fixture portion 116 ofthe fuel injector and through the heat exchanger portion 108 to thenozzle outlet 118. The air channel 110 passes from the heat exchangerportion 108, through the fixture portion 116, to an air channel outlet120. The respective inlet 114 of the fuel channel 112 is connected tothe fuel manifold 104 for fluid communication of fuel from the fuelmanifold 104 to the nozzle outlet 118 for combustion. The respectiveoutlet 120 of the air channel 110 is connected to the air manifold 102for fluid communication of air from the heat exchanger portion 108 intothe air manifold 102.

An air valve 122 is operatively connected to an outlet 124 of the airmanifold 102 for controlling release of air from the air manifold 102,e.g. for use as cooling or just compressed air in aircraft or enginesystems 126. A controller 128 is operatively connected to the air valve122. The controller 128 includes machine readable instructionsconfigured to control the air valve 122 to regulate flow of air throughthe air valve 122 based on fuel temperatures in the fuel channel 112.The machine readable instructions are configured to cause the controller128 to flow air through the air valve 122 in a heat exchange mode, asshown in FIG. 1 , if a fuel temperature in the fuel injectors 106 isbelow a predetermined fuel temperature, e.g. to avoid over heating thefuel in the fuel channel 112.

With continued reference to FIG. 1 , the machine readable instructionsare configured to cause the controller 128 to vary air flow rate throughthe air valve 122 in the heat exchange mode to increase air flow throughthe air valve 122 to the systems 126 while maintaining fuel temperaturebelow the predetermined limit. A temperature sensor 130 can be mountedin at least one of the fuel injectors 106 operative to produce a signalindicative of fuel temperature in the fuel channels 112 of the fuelinjectors 106, especially in the fuel injector or injectors 106 thatinclude heat exchanger portions 108. The controller 128 is operativelyconnected to receive the signal, wherein the machine readableinstructions are configured to control the air flow rate through the airvalve 122 based on the signal. For best control, the temperature sensor130 should be located as near as possible to the outlet of the fuelchannel 112, e.g. in the nozzle tip. This is where the fuel temperatureswill be highest and best not to exceed. However, locating thetemperature sensor 130 in other locations such in the heat exchangerportion 108 as shown in FIG. 1 , the temperature at the tip can beinferred based on fuel flow rates and heat transfer rates.

There is another way to control this system without a direct sensor 130.That is the controller 128 can just know the operational point of theinjectors 106, such as by using a pre-programmed digital model of heattransfer analysis considering the engine operating conditions, which maybe used to self-diagnose the required flow and directions. For example,if the controller 128 knows the engine is at a takeoff condition, itknows the incoming air is hot, but also has a lot of fuel, so maybe itmay be still acceptable to operate in the mode of FIG. 1 . While on aslam deceleration, the air may still be hot, but fuel flow rate isslowed down, thus overheating could occur if heat exchange in theinjectors 106 is active, so one of the modes below may be used in thatengine state. There are also mission dependent operations where it maybe desirable to override the temperature limit. For example, the pilotor platform needs to temporarily exceed the temperature limits, but fora short period of time if that exceedance is acceptable to the system.An example would be for providing cooling for a laser for a shortduration.

If the fuel temperature is low enough to be able to absorb more heat,and compressor air is also not yet too hot, the fuel can exchange heatwith the air. This cooled air can then be used to cool or justpressurize external components 126. The air valve 122 can be used tocontrol the air flow rate to not overheat the fuel, while alsopotentially maximizing cooling based on feedback from the temperaturesensor 130.

With reference now to FIG. 2 , the machine readable instructions areconfigured to cause the controller to prevent air flow through the airvalve 102 in a neutral mode. The neutral mode can be useful if thecompressor discharge air temperatures are too high, and/or the fueltemperatures in the fuel channel 112 is too high. In the neutral mode,air gaps in the fuel injectors 106 can insulate fuel in the fuelinjectors 106 from the compressor discharge air outside the fuelinjectors 106. In particular, for any of the fuel injectors 106 thatinclude a heat exchanger portion 108, the air channel 110 with stagnantair therein can serve as an insulation gap for the respective fuelchannel 112. If fuel cooling mode (as described below) is not needed forengine operation, the neutral mode can be used rather than activecooling.

Referring now to FIG. 3 , there is also an optional fuel cooling mode.An auxiliary source 132 of conditioned, compressed air is included,selectively in fluid communication with the air manifold 122. Themachine readable instructions are configured to prevent air flow out ofthe air manifold 102 and instead flow air from the auxiliary source 132into the air manifold 102 and heat exchanger portion(s) 108 in a fuelcooling mode. The auxiliary source 132 of air includes an air coolingheat exchanger 134 separate from the fuel injectors 106 and operative tocool compressor discharge air from the compressor (the diffuser 136 isshown in FIGS. 1-3 ). A boost compressor 138 is connected in fluidcommunication with the air cooling heat exchanger 134 and operative toraise pressure in a flow of air from the air cooling heat exchanger 134to a pressure above the compressor discharge air pressure. The boostcompressor 134 is in fluid communication with the air valve 122 (or aseparate air valve of the air manifold 102 in addition to the air valve122). The air valve 122 is configured to block flow out of the airmanifold 102 and admit air into the air manifold 102 from the boostcompressor 138 for active cooling of fuel in the at least one fuelinjector 106 with a heat exchanger portion 108 in the fuel cooling mode.The controller 128 is configured to initiate the fuel cooling mode basedon a signal received from at least one temperature sensor 130 in theplurality of fuel injectors 106.

If the fuel temperature is already hot, and the compressor discharge airis also very hot, it may be advantageous to actively cool the fuelinjectors 106. This can be done by running the air circuit in reverse tocool off the fuel in the fuel injectors 106. The amount of air neededcan be determined and controlled using the air valve 122 and temperaturesensor 130 for feedback.

With reference again to FIG. 1 , the system 100 includes an engine case140. The heat exchanger portion 108 of the at least one fuel injector106 in the plurality of fuel injectors 106 is inside the engine case140. The air manifold 102 and fuel manifold 104 are outside the enginecase 140. The air manifold 102 and the fuel manifold 104 are spacedapart from one another, with a gap 142 between the air manifold 102 andthe fuel manifold 104. A combustor dome wall 144 is included inside theengine case. A combustion space 146 of a combustor 148 is defined on adownstream side of the combustor dome wall 144. Each fuel injector 106in the plurality of fuel injectors includes a nozzle outlet 150 mountedproximate to and in fluid communication through the combustor dome wall144 operative to issue fuel into the combustion space 146. An inlet 152to the air channel 110 of heat exchanger portion(s) 108 is locatedupstream of the compressor side of the combustor dome wall 144 oppositethe combustion space 146.

A method of heat exchange for a gas turbine engine includes collectingair from a respective fuel air heat exchanger portion (e.g. heatexchanger portion 108) of at least one fuel injector in a plurality offuel injectors (e.g. fuel injectors 106) into an air manifold (e.g. airmanifold 102). The method includes supplying air from the air manifoldto one or more external compressed air systems (e.g., systems 126) in aheat exchange mode, as shown in FIG. 1 .

The method includes varying flow of air through the air manifold basedon fuel temperature in the plurality of fuel injectors. Modulating flowof air includes increasing flow of air through the manifold if fueltemperature in the plurality of fuel injectors permits without exceedinga predetermined limit on fuel temperature.

The method can include preventing air flow through the air manifold in aneutral mode, as shown in FIG. 2 . In a fuel cooling mode, as shown inFIG. 3 , the method can include preventing air flow out of the airmanifold and instead flowing air into the air manifold. In the coolingmode, cooling air from the air manifold is flowed into the plurality offuel injectors. The method includes supplying cooling air to the airmanifold from compressor discharge air that is pressure boosted to abovecompressor discharge air pressure. The method includes cooling pressureboosted, compressor discharge air upstream of the air manifold in thefuel cooling mode, e.g. using boost compressor 138 and cooling heatexchanger 134.

Potential benefits include a high pressure, cooled air stream availablefor cooling other parts of the engine or airplane. This arrangementpotentially allows the maximum amount of heat to be extracted from thehigh pressure/high temperature compressed air without excessive fueltemperatures. Active temperature control provides prevention ofoverheating fuel which may include the operation of the air valve andalso temperature feedback from within one or more fuel injectors.Reverse operation, e.g. in the fuel cooling mode, can enable the heatexchanger to be used to cool the fuel injectors with cold incoming air,as well as an air assist to provide additional fuel atomization, forexample at engine startup or altitude relight.

As will be appreciated by those skilled in the art, aspects of thepresent disclosure may be embodied as a system, method or computerprogram product. Accordingly, aspects of this disclosure may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.), or anembodiment combining software and hardware aspects, all possibilities ofwhich can be referred to herein as a “circuit,” “module,” or “system.” A“circuit,” “module,” or “system” can include one or more portions of oneor more separate physical hardware and/or software components that cantogether perform the disclosed function of the “circuit,” “module,” or“system”, or a “circuit,” “module,” or “system” can be a singleself-contained unit (e.g., of hardware and/or software). Furthermore,aspects of this disclosure may take the form of a computer programproduct embodied in one or more computer readable medium(s) havingcomputer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thisdisclosure may be written in any combination of one or more programminglanguages, including an object oriented programming language such asJava, Smalltalk, C++ or the like and conventional procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The program code may execute entirely on the user's computer,partly on the user's computer, as a stand-alone software package, partlyon the user's computer and partly on a remote computer or entirely onthe remote computer or server. In the latter scenario, the remotecomputer may be connected to the user's computer through any type ofnetwork, including a local area network (LAN) or a wide area network(WAN), or the connection may be made to an external computer (forexample, through the Internet using an Internet Service Provider).

Aspects of this disclosure may be described above with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of thisdisclosure. It will be understood that each block of any flowchartillustrations and/or block diagrams, and combinations of blocks in anyflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inany flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified herein. Those having ordinaryskill in the art understand that any numerical values disclosed hereincan be exact values or can be values within a range. Further, any termsof approximation (e.g., “about”, “approximately”, “around”) used in thisdisclosure can mean the stated value within a range. For example, incertain embodiments, the range can be within (plus or minus) 20%, orwithin 10%, or within 5%, or within 2%, or within any other suitablepercentage or number as appreciated by those having ordinary skill inthe art (e.g., for known tolerance limits or error ranges).

The articles “a”, “an”, and “the” as used herein and in the appendedclaims are used herein to refer to one or to more than one (i.e., to atleast one) of the grammatical object of the article unless the contextclearly indicates otherwise. By way of example, “an element” means oneelement or more than one element.

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e., “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.”

Any suitable combination(s) of any disclosed embodiments and/or anysuitable portion(s) thereof are contemplated herein as appreciated bythose having ordinary skill in the art in view of this disclosure.

The methods and systems of the present disclosure, as described aboveand shown in the drawings, provide for a supply of cool, compressed airfrom compressor discharge air for use on an engine and/or aircraft,using heat exchangers in the fuel injectors, as well as techniques forcooling fuel in the fuel injectors. While the apparatus and methods ofthe subject disclosure have been shown and described with reference topreferred embodiments, those skilled in the art will readily appreciatethat changes and/or modifications may be made thereto without departingfrom the scope of the subject disclosure.

What is claimed is:
 1. A method of heat exchange for a gas turbineengine comprising: collecting air from a fuel air heat exchanger portionof at least one fuel injector in a plurality of fuel injectors into anair manifold; and supplying air from the air manifold to one or moreexternal compressed air systems in a heat exchange mode.
 2. The methodas recited in claim 1, further comprising varying a flow of air throughthe air manifold based on fuel temperature in the plurality of fuelinjectors.
 3. The method as recited in claim 2, wherein modulating flowof air includes increasing flow of air through the manifold if a fueltemperature in the plurality of fuel injectors permits without exceedinga predetermined limit on fuel temperature.
 4. The method as recited inclaim 2, further comprising preventing air flow through the air manifoldin a neutral mode.
 5. The method as recited in claim 1, furthercomprising preventing air flow out of the air manifold and to flow airinto the air manifold in a fuel cooling mode.
 6. The method as recitedin claim 5, wherein in the fuel cooling mode, cooling air from the airmanifold is flowed into the plurality of fuel injectors.
 7. The methodas recited in claim 6, further comprising supplying cooling air to theair manifold from compressor discharge air that is pressure boosted toabove compressor discharge air pressure.
 8. The method as recited inclaim 7, further comprising cooling pressure boosted, compressordischarge air upstream of the air manifold in the fuel cooling mode.